Aspidistra was a British mediumwave radio transmitter used for black propaganda and military deception purposes against Nazi Germany during World War II. At one time, it was the most powerful broadcast transmitter in the world. Its name - after the popular foliage houseplant - was inspired by the comic song The Biggest Aspidistra in the World, best known as sung by Gracie Fields.
The transmitter was installed in 1942 at a purpose-built site near Crowborough in southeast England. This was equipped with other mediumwave and shortwave transmitters, which also used the Aspidistra name, being known as ASPI 2, ASPI 3, ASPI 4, etc. However, when the name Aspidistra was used on its own it always referred to the original mediumwave transmitter (ASPI 1).
After the war, Aspidistra and other transmitters at Crowborough were used for BBC External Service broadcasts to Europe. The station closed in 1982. Aspidistra broadcast on mediumwave AM with 600 kW of power. The transmitter (originally 500 kW) had been built by RCA for WJZ radio in Newark, New Jersey. But at the prompting of Congress spurred on by competition, the Federal Communications Commission later imposed a 50-kW power limit on all US stations. RCA was therefore glad to sell it overseas and the British Secret Service bought it for £165,000.
In addition to its high power, Aspidistra could be re-tuned quickly to a new frequency (position on the dial). This was of great use in its secret wartime work and was unusual for a mediumwave transmitter, as they generally operate on a fixed frequency throughout their working life.
Its antenna was three guyed masts, each 110 m (360 ft) tall. The 1940s Art Deco style transmitter building was in an underground shelter which had been excavated by a Canadian army construction unit. Power for the transmitter was supplied from a single large Crossley-Premier 16 cylinder heavy oil engine.
Alongside the original Aspidistra, other mediumwave and shortwave transmitters were installed over the years. These included two Doherty 250 kW mediumwave units, whose outputs could be combined to give 500 kW on a single frequency.